Table of Contents - OBD China
Table of Contents - OBD China
Table of Contents - OBD China
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2.4 <strong>OBD</strong> II Readiness Monitors<br />
An important part <strong>of</strong> a vehicle’s <strong>OBD</strong> II system is the Readiness<br />
Monitors, which are indicators used to find out if all <strong>of</strong> the emissions<br />
components have been evaluated by the <strong>OBD</strong> II system. They are<br />
running periodic tests on specific systems and components to ensure<br />
that they are performing within allowable limits.<br />
Currently, there are eleven <strong>OBD</strong> II Readiness Monitors (or I/M<br />
Monitors) defined by the U.S. Environmental Protection Agency<br />
(EPA). Not all monitors are supported by all vehicles and the exact<br />
number <strong>of</strong> monitors in any vehicle depends on the motor vehicle<br />
manufacturer’s emissions control strategy.<br />
Continuous Monitors -- Some <strong>of</strong> the vehicle components or systems<br />
are continuously tested by the vehicle’s <strong>OBD</strong> II system, while others<br />
are tested only under specific vehicle operating conditions. The<br />
continuously monitored components listed below are always ready:<br />
1)Misfire<br />
2)Fuel System<br />
3)Comprehensive Components (CCM)<br />
Once the vehicle is running, the <strong>OBD</strong> II system is continuously<br />
checking the above components, monitoring key engine sensors,<br />
watching for engine misfire, and monitoring fuel demands.<br />
Non-Continuous Monitors -- Unlike the continuous monitors, many<br />
emissions and engine system components require the vehicle to be<br />
operated under specific conditions before the monitor is ready. These<br />
monitors are termed non-continuous monitors and are listed below:<br />
4